1. Field of the Invention
The present invention is related to a method and device for adaptively reducing the noise in speech communication applications.
2. Related Art
There are a variety of medical implants which deliver electrical stimulation to a patient or recipient (“recipient” herein) for a variety of therapeutic benefits. For example, the hair cells of the cochlea of a normal healthy ear convert acoustic signals into nerve impulses. People who are profoundly deaf due to the absence of destruction of cochlea hair cells are unable to derive suitable benefit from conventional hearing aid systems. Prosthetic hearing implant systems have been developed to provide such persons with the ability to perceive sound. Prosthetic hearing implant systems bypass the hair cells in the cochlea to directly deliver electrical stimulation to auditory nerve fibers, thereby allowing the brain to perceive a hearing sensation resembling the natural hearing sensation.
The electrodes implemented in stimulating medical implants vary according to the device and tissue which is to be stimulated. For example, the cochlea is tonotopically mapped and partitioned into regions, with each region being responsive to stimulate signals in a particular frequency range. To accommodate this property of the cochlea, prosthetic hearing implant systems typically include an array of electrodes each constructed and arranged to deliver an appropriate stimulating signal to a particular region of the cochlea.
To achieve an optimal electrode position close to the inside wall of the cochlea, the electrode assembly should assume this desired position upon or immediately following implantation into the cochlea. It is also desirable that the electrode assembly be shaped such that the insertion process causes minimal trauma to the sensitive structures of the cochlea. Usually the electrode assembly is held in a straight configuration at least during the initial stages of the insertion procedure, conforming to the natural shape of the cochlear once implantation is complete.
Prosthetic hearing implant systems typically have two primary components: an external component commonly referred to as a speech processor, and an implanted component commonly referred to as a receiver/stimulator unit. Traditionally, both of these components cooperate with each other to provide sound sensations to a recipient.
The external component traditionally includes a microphone that detects sounds, such as speech and environmental sounds, a speech processor that selects and converts certain detected sounds, particularly speech, into a coded signal, a power source such as a battery, and an external transmitter antenna.
The coded signal output by the speech processor is transmitted transcutaneously to the implanted receiver/stimulator unit, commonly located within a recess of the temporal bone of the recipient. This transcutaneous transmission occurs via the external transmitter antenna which is positioned to communicate with an implanted receiver antenna disposed within the receiver/stimulator unit. This communication transmits the coded sound signal while also providing power to the implanted receiver/stimulator unit. Conventionally, this link has been in the form of a radio frequency (RF) link, but other communication and power links have been proposed and implemented with varying degrees of success.
The implanted receiver/stimulator unit traditionally includes the noted receiver antenna that receives the coded signal and power from the external component. The implanted unit also includes a stimulator that processes the coded signal and outputs an electrical stimulation signal to an intra-cochlea electrode assembly mounted to a carrier member. The electrode assembly typically has a plurality of electrodes that apply the electrical stimulation directly to the auditory nerve to produce a hearing sensation corresponding to the original detected sound.